1. Field of the Invention
The present invention relates to coaxial speakers and more particularly, a coaxial speaker assembly that reduces sound distortion, sound time delay, and improves polar response. The coaxial speaker assembly of the present invention includes a step-down ledge positioned adjacent to a baffle for reflecting sound waves diffracting around the baffle.
2. Description of the Prior Art
Commonly, a coaxial speaker assembly is broadly comprised of a high-frequency speaker, such as a tweeter, fitted within a lower-frequency speaker, such as a woofer, wherein both speakers lie on a common axis. The high-frequency speaker often has a baffle circumferentially positioned around a high-frequency diaphragm. The baffle serves two purposes: (1) to direct sound waves emanating from the high-frequency diaphragm out towards a listener; and (2) to prevent mixing of the sound waves emanating from the high-frequency diaphragm and an underlying low-frequency diaphragm.
The baffle is limited, though, in the sound waves it can direct. In operation, most of the sound waves project outwards such that the listener hears the high-frequency waves without sound distortion or sound time delay. However, a portion of the sound waves diffract around an edge of the baffle and downwards toward the moving low-frequency diaphragm. These waves are then reflected off the moving low-frequency diaphragm and back out towards the listener. A first problem resulting from reflection off the low-frequency diaphragm is sound distortion due to a frequency shift of the low-frequency sound waves. Because the low-frequency diaphragm is moving, the waves reflecting off the diaphragm undergo a frequency shift, similar to a Doppler effect, which produces the distorted sound. Second, the time necessary for the sound waves to travel down towards the low-frequency diaphragm and back out towards the listener results in the sound waves not being heard at the correct time. A third problem arises due to the low-frequency diaphragm being positioned at an angle that results in sound wave reflection at an undesirable angle, thus distorting polar response. Polar response is a measurement of how the sound waves produced by a speaker sound, i.e., its tonal characteristics, in relation to where a listener is standing in a room.
To remedy sound distortion, sound time delay, and polar response distortion due to reflection at an undesirable angle, common prior art devices round off or bevel, the baffle's edge. The baffle's edge may also have an included angle, depending on the size and style of the speaker. Unfortunately, none of these devices sufficiently reduces sound distortion, sound time delay, and polar response distortion.
There is therefore a need for an improved coaxial loudspeaker assembly that does not suffer from the limitations of conventional coaxial speaker assembly designs.